Usually, in an electronic coin checker, the examined coin is guided by a coin distributor either into one or more acceptance shafts or even into a return shaft, depending on whether certain acceptance criteria are met. This occurs via deflection units, such as flaps for example, which are driven by electromagnets. Generally, a device for detecting the passage of a coin through a coin shaft is arranged in the acceptance shaft below the deflection unit. The device for detecting the passage of a coin through a coin shaft, e.g. a light barrier, checks the presence of the accepted coin and sends a corresponding signal to a connected evaluation unit if a coin has passed into the light barrier and/or out of the light barrier. When the coin enters the light barrier, the evaluation unit interrupts the triggering of the electromagnet such that the deflection unit (e.g. flap) assumes its rest position again and, when the coin exits from the light barrier, generates the credit signal.
In coin-operated machines which have a coin distributor, attempts are repeatedly made to achieve credit signals fraudulently by suspending coins on threads and trying to withdrawn the suspended coins after they have been dipped into the light barrier. If a coin that is dipped into the light barrier is located in the region of the flap, manipulation is possible since the flap is prevented from reaching its rest position by the coin. Therefore, an exit path for the coin kept open by the coin itself hanging on the thread.
One solution to this problem consists in arranging the light barrier so far below the flap that the latter can reach its rest position by the time the coin dips into the light barrier (because the light barrier lies more than the diameter of a coin below the flap). Withdrawing the coin is then reliably prevented by the closed flap.
However, often the space available below the flap is not sufficient to thus achieve the necessary spacing between the deflection unit (flap) and the device for detecting the passage of a coin (the light barrier of the prior art). Another solution for preventing manipulation includes providing a light barrier arrangement with which the direction in which the coin dips into the light barrier and leaves it again can also be determined. This is possible for example by means of two light barriers arranged one behind the other. In this way, however, the problem of a lack of installation space is possibly made even greater such that the expert is in practice often obliged, in order to optimize installation space, to make concessions to safety requirements.
The document U.S. Pat. No. 5,485,906 shows a coin distributor of this type. It contains on the one hand a displaceable deflection member for sorting coins into different coin shafts. Moreover a device is shown for detecting the passage of a coin through a coin shaft, this device including at least one emitter, a beam deflector and a beam receiver. This beam deflector is secured to a different flap from the deflection member, it being intended primarily that manipulation by withdrawing an inserted coin using a thread should be prevented with the aid of this flap. This document according to the prior art thus shows a device which is mechanically relatively extravagant and large-scale.